A fluoroscopic imaging system provides a real time X-ray image of an appropriate part of an examinee or a patient on a monitor display using a television system, and is widely used in various clinical fields including angiography or interventional radiography (IVR). Among the IVR is included a percutaneous transluminal coronary angioplasty (PTCA).
In a PTCA, a catheter is inserted in the patient's circulatory system toward the heart, an inflatable balloon at the end of the catheter is placed at a stenosis in the coronary, and the balloon is inflated several times to cure the stenosis. The steering operation of the balloon catheter in the circulatory system and the inflating operation of the balloon at the stenosis are conducted with the assistance of a fluoroscopic image. The fluoroscopic image in this case is normally obtained using a continuous X-ray or a pulsewise X-ray of 15-30 pulses per second (pps). Since the inflation of the balloon needs strict time control including the length of inflating time and the number of times of the inflation, and they must be recorded, a stopwatch or a timer equipped in the fluoroscopic imaging system is used.
Since an IVR generally requires difficult techniques, and thus the fluoroscopic imaging lasts a long time (sometimes several times as long as that of a normal angiography), the X-ray dose of the patient would be a problem.